Inverting tidal velocity from geomagnetic satellite by nonlinear method

This study presents an inversion method to recover the tidal flow velocity using tidal signals extracted from geomagnetic satellite dataset. By integrating the latest Earth conductivity profile and the Earth's magnetic field model, the limited memory quasi-Newton method (L-BFGS) is used to directly invert seawater flow velocities. We used the radial component of the induced magnetic field as the observed data, constructed an L₂-norm-based data misfit term using theoretical response and observed data, and applied smoothness constraints to the ocean flow velocity. The results agree well with the widely used HAMTIDE model in low- and mid-latitude regions, which is attributed to Macau Science Satellite-1's (MSS-1) unique low-inclination orbit of full coverage in these areas. These findings underscore MSS-1's potential to advance research on tidal-induced magnetic fields and their applications in ocean dynamics studies.